Fusible coupling for fire alarm circuits



NOV. 9, 1937. STAUFFER 2,098,680

FUSIBLE COUPLING FOR FIRE ALARM CIRCUITS Filed Nov. 27, 1935 7 @[9/2 5 id War INVENTOR ATTOR N EY Patented Nov. 9, 1937 UNITED STATES PATENT OFFICE FUSIBLE COUPLING FOR FIRE ALARM CIRCUITS The present invention relates to a new and improved fusible coupling and is especially adapted for an electric fire alarm system of the closed circuit type.

It is the primary object of this invention to provide a coupling constructed of non-conductive, combustible material that shall be inexpensive in construction and reliable in operation.

It is a, further object to provide a coupling that is easily assembled and adapted to be positioned within the conductor or line circuit, and will operate to break the circuit as soon as heat of a predetermined temperature is applied thereto.

With these and other objects in view, this invention consists of certain novel features of construction, combination and arrangement of parts to be hereinafter more fully described and explained.

For a complete understanding of the invention,

reference is to be had to the following description and accompanying drawing, in which:

Figure 1 is a top plan view of the invention in use in a system of the closed circuit type.

Figure 2 is a side elevation view thereof.

Figure 3 is a partial sectional view disclosing the coupling, and the terminals in longitudinal cross section.

Figure 4 is a longitudinal sectional view through the coupling.

Figure 5 is a fragmentary view of the coupling and one terminal, and

Figure 6 is a sectional view of a modified coupling illustrating a pair of pins for insulating purposes.

Referring in detail tothe drawing, the numeral It indicates the body of the coupling which may be constructed of a non-conductive, combustible material, such as fibre and bakelite and is preferably relatively thick and of flat ring or washer shape in configuration. At diametrically opposite sides of the body ID, are provided a pair of threaded openings II and I2, adapted to receive the terminals I3 and 14 having reduced ends 15 and i6.

Referring to Figure 4, it is to be noted that the terminals are screw-threadedly engaged in the coupling l0 and may be adjusted so that the reduced ends l5 and I6 are maintained in spaced relation a predetermined distance. This is made possible due to the adjustability of the terminals l3 and M.

The terminals l3 and I4 are further provided with bores or recesses I! and I8, for receiving the conducting wires H of the line circuit.

In order to maintain a proper contact, the

wires 19 are sealed within the recesses l1 and I8, with any suitable sealing means, but it is preferred that said sealing element be of a character readily fusible and of a low' melting point. In Figure 4, the wire is shown as sealed at 20 within 5 the recess and at 2| at the point of the entrance of the wire within the recess.

The coupling may be insulated as illustrated in the modified form of Figure 6 in the event, it becomes necessary to lay the same upon or ad- 10 jacent to a flat surface, as shown and for accomplishing this purpose, it is desired to provide a pair of recesses 22 extending transversely through the body and opposite points, the recesses receiving a pair of pins or posts 23 which are of in- 15 sulating material. It is to be understood that the use of the insulating pins 23 is optional, but they should be of suflicient length or thickness to separate or elevate the coupling from contact with any foreign conductor. 20

In the use of the invention, one or more of the improved fusible couplings may be positioned at desired points in the system. After the terminals .are properly adjusted so that the contact points l5 and I6 are spaced a predetermined distance, 25 solder or other fusible element 24 of a low melting point is poured within the opening 25, encasing and bridging the two terminals 15 and I6, thus converting the coupling into a conductor of electricity. 30

As above indicated, the hollow end of the terminals I3 and I4 permit the insertion and soldering of the line wires which form a part of the circuit.

In operation, when heat of a predetermined 35 temperature is created, the fusible material 24 will melt, thus breaking the contact with the two terminals and converting the coupling to a nonconductor, thereby breaking the circuit.

Heat and flame will also destroy the body l0, thereby giving added assurance of the operation of the system.

It is also to be considered that the system is rendered additionally operative due to the fact 45 that the wires encased within the hollow end of the terminal are surrounded by a fusible element of a low melting point, such as solder, thus mak-- ing installation easier under certain conditions. Again, by employing the pins or posts 23, the 50 coupling is elevated above a fiat surface, as shown in Figure 6, so as to facilitate the melting or removal of the plug or fusible material 24, as will be apparent.

While the invention is shown in use with an 55 electric fire alarm system, it is to be understood that it is applicable to other uses.

What I claim is:

1. A fusible coupling comprising a relatively thick flat ring-like body of non-conductive, combustible material, said body having a central opening therein and openings through diametrically opposite sides thereof for communication with the central opening, av pair of terminals engaged within the diametrically opposed openings and having reduced inner ends extending into the central opening and spaced from each other, said terminals having longitudinal bores extending into the outer ends thereof for receiving line wires therein, fusible means for seal ing said wires within the bores andfusible means in the form of a plug filling the central opening and encasing said reduced ends.

2. A fusible coupling comprising a relatively thick flat ring-like body of non-conductive, combustible material, said body having a central opening therein and openings through diametrically opposite sides thereof for communication with the central opening, a pair of terminals engaged within the diametrically opposed openings and having reduced inner ends extending into the central opening and spaced from each other, said terminalshaving-longitudinal bores extending into the outer ends: thereof for receiving line wires therein, fusible means for sealing said Wires within the bores, and fusible means in the form of a plug filling the central opening and encasing said reduced ends, and posts of insulating material secured to and extending at right angles from the body for elevating and spacing the coupling from adjacent surfaces to insulate the same therefrom.

GLEN D. STAUFFER. 

